Valence electron

In chemistry, a valence electron is an electron that is associated with an atom, and that can participate in the formation of a chemical bond; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair. The presence of valence electrons can determine the element's chemical properties and whether it may bond with other elements: For a main group element, a valence electron can only be in the outermost electron shell. In a transition metal, a valence electron can also be in an inner shell.

An atom with a closed shell of valence electrons (corresponding to an electron configuration s2p6) tends to be chemically inert. Atoms with one or two more valence electrons than are needed for a "closed" shell are highly reactive because it requires relatively low energy (compared to the lattice enthalpy) to remove the extra valence electrons to form a positive ion. Atoms with one or two valence electrons fewer than are needed to form a closed shell are also highly reactive because of a tendency either to gain the missing valence electrons (thereby forming a negative ion), or to share valence electrons (thereby forming a covalent bond).

Valence electron

In chemistry, a valence electron is an electron that is associated with an atom, and that can participate in the formation of a chemical bond; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair. The presence of valence electrons can determine the element's chemical properties and whether it may bond with other elements: For a main group element, a valence electron can only be in the outermost electron shell. In a transition metal, a valence electron can also be in an inner shell.

An atom with a closed shell of valence electrons (corresponding to an electron configuration s2p6) tends to be chemically inert. Atoms with one or two more valence electrons than are needed for a "closed" shell are highly reactive because it requires relatively low energy (compared to the lattice enthalpy) to remove the extra valence electrons to form a positive ion. Atoms with one or two valence electrons fewer than are needed to form a closed shell are also highly reactive because of a tendency either to gain the missing valence electrons (thereby forming a negative ion), or to share valence electrons (thereby forming a covalent bond).

Latest News for: valence electrons

Isotopic fractionation in the photodissociation of N2 could explain the considerable variation in the 14N/15N ratio in different regions of our galaxy. We previously proposed that such an isotope effect is due to coupling of photoexcited bound valence and Rydberg electronic states in the frequency range where there is strong... ....

The new material has an unusually small band gap [3] of around 2.4electron volts (eV), meaning that it can absorb visible light with a wavelength of around 500 nanometers (nm) ... Refers to the difference in energy of an electron in the valence band and the conduction band, which indicates the conductivity of a material ... A property whereby electrons are held tightly to the nucleus....

The electrical conductivity of a semiconductor is controlled by its band gap, which is the energy difference between its valence and conduction bands; a narrow band gap results in increased conductivity because it is easier for an electron to move from the valence to the conduction band ... their application range, particularly in flexible electronics....

NEW DELHI. Board exams are going on. The students, who are appearing for CBSEClass 10th and 12th exams are nervous and busy in giving final preparation to their respective papers ...All the best!. Prepare intelligently ... A metal ion Mn+ having d4 valenceelectronic configuration combines with three bidentate ligands to form a complex compound ... (i) Write the electronic configuration of d4 ion ... (i) has the maximum number of unpaired electrons?....

Support For Healthy Brain Functioning ... A free radical is a molecule or atom presenting with an unpaired valenceelectron.� All human beings have free radicals and these elements can damage the health of the body by speeding up the aging process and increasing the risk of disease formation.� Studies find that the use of fulvic acid can resist the effects of the free radicals by containing antioxidants ... 6.� Improved Skin Care ... ....

Vanadium flow batteries use the multiple valence states of vanadium to store and release charges. Energy is stored by providing electrons making V(2+,3+), and energy is released by losing electrons to form V(4+,5+) ... When pumped into a reactor, the two solutions flow adjacent to each other past a membrane and generate a charge by moving electrons back and forth during charging and discharging....

It is made up of excitons, particles that are formed in a very strange quantum mechanical pairing, namely that of an escaped electron and the hole it left behind. It defies reason, but it turns out that when an electron, seated at the edge of a crowded-with-electronsvalence band in a semiconductor, gets excited and jumps over the energy gap to the otherwise empty conduction band, it leaves behind a “hole” in the valence band....

It defies reason, but it turns out that when an electron, seated at the edge of a crowded-with-electronsvalence band in a semiconductor, gets excited and jumps over the energy gap to the otherwise empty conduction band, it leaves behind a "hole" in the valence band.&nbsp;That hole behaves as though it were a particle with positive charge, and it attracts the escaped electron....

It is made up of excitons, particles that are formed in a very strange quantum mechanical pairing, namely that of an escaped electron and the hole it left behind. It defies reason, but it turns out that when an electron, seated at the edge of a crowded-with-electronsvalence band in a semiconductor, gets excited and jumps over the energy gap to the otherwise empty conduction band, it leaves behind a "hole" in the valence band....

Ithaca NY (SPX) Nov 08, 2017. The concept of "valence" - the ability of a particular atom to combine with other atoms by exchanging electrons - is one of the cornerstones of modern chemistry and solid-state physics. Valence controls crucial properties of molecules and materials, including their bonding, crystal structure, and electronic and magnetic properties. Four decades ago, a class of materials called "mixed ... ....

This story was reported for radio by Elissa Nadworny and for the web by Jon Marcus of the Hechinger Report. In her spotless camouflage uniform, MonicaCallan stood apart from the dirty and exhausted-looking first-year cadets at the U.S. AirForceAcademy who had just endured nearly three hours on the obstacle course. Monica Callan (right) marches with first-year cadets ... "I was, like, 'Why don't I remember what valenceelectrons are?' " ... ....